Title

The Neoproterozoic Hüttenberg δ13C anomaly: Genesis and global implications

Document Type

Article

Publication Date

8-1-2018

Abstract

© 2018 Elsevier B.V. The Neoproterozoic Hüttenberg Formation in northeastern Namibia records a remarkable δ13Ccarb positive excursion with a sustained plateau of values up to +12‰ (i.e., the Hüttenberg anomaly). High-resolution chemostratigraphic analyses of drill core samples spanning the upper Elandshoek and Hüttenberg formations reveal multiple new observations: (1) overall high but oscillatory δ13Ccarb values; (2) δ18Ocarb values ranging from −8‰ to −2‰; (3) significant enrichment of 13C in organic carbon and a broad co-variation between δ13Ccarb and δ13Corg; (4) a profound negative excursion in δ34Spyrite from +30‰ to −10‰; (5) an overall inverse δ13C–δ34S relationship; and (6) 87Sr/86Sr values down to 0.7074 in limestone samples. The new data suggest that the Hüttenberg anomaly records dynamic fluctuations in marine redox conditions, which may include an oxygenation event during the height of the δ13Ccarb positive excursion and a deoxygenation event at its termination. The δ34Spyrite negative excursion suggests the buildup of the marine sulfate reservoir, likely due to enhanced pyrite oxidation during the oxygenation event. The δ34Spyrite increase at the end of the Hüttenberg anomaly may result from a seawater sulfate concentration drawdown towards pre-anomaly conditions. On one hand, the Hüttenberg anomaly may reflect restricted basin signals that are deviated from the Ediacaran open ocean; on the other hand, the Ediacaran Hüttenberg anomaly, together with the Cryogenian δ13Ccarb positive excursions, suggests a stepwise pattern of the Neoproterozoic Oxygenation Event. Both local and global environmental factors may have contributed to the Hüttenberg anomaly. The Hüttenberg anomaly therefore represents a local enhancement of global oxygenation signals. Our data support the emerging view that the Neoproterozoic Oxygenation Event may have facilitated the evolution of early life at that time.

Publication Source (Journal or Book title)

Precambrian Research

First Page

242

Last Page

262

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